Analysis of spectral parameters of trans- and cis-silyl substituted 1,2-dihalogenoethenes including one-bond CC spin-spin coupling constants across double bonds

Article abstract of DOI:10.1016/0022-328X(89)85328-8

Some trans- and cis-1-trialkylsilyl-1,2-dihalogenoethenes have been synthesized and their 13C and 1H NMR spectra recorded.The compounds studied readily undergo reversible cis-trans isomerization, the cis isomers being thermodynamically more stable than the trans isomers.The value of ³J(SiH_α)_trans is about twice as large as that of ³J(SiH_α)_cis, and the values of ²J(C_βH_α)_trans is about one-tenth that of ²J(C_βH_α)_cis and this allows ready assignment of the configuration.The one-bond spin-spin coupling constants between the ethylenic carbons depend on the electronegativities of the substituents, trans ¹J(C=C) in most cases being larger than ¹J(C=C)_cis.